The evolution of the CPV is the dCPV. duplex Constructive Pressure Vessel.
- the inner segment contains the hydrogen gas.
- the outer segment contains nitrogen gas.
This way, we have solved the remarks that came up when we disclosed that we are going to store hydrogen gas in a tower structure.
Issues with steel embrittlement, sealing and gas permeation were resolved with the dCPV assembly.
The inner vessel containing the hydrogen gas, is a fully welded stainless steel tube, with a rather thin wall. If the hydrogen permeates through the stainless steel wall, it will come into the inert nitrogen gas layer.
Why can we use a thin wall for the inner vessel?
If we balance the pressure of the N2 and H2 in the same pressure range, the pressure difference (ca 5 to 10 bar dP) will be small, so a thin wall is sufficient.
It is the outer wall (in contact with N2) that takes all the mechanical loads of the working pressure and weights.